Internal Medicine Clinical Update: Hyperadrenocorticism

Hyperadrenocorticism (HAC) is a common endocrinopathy. More often or affecting middle-aged to older dogs. In the last decade there has been extensive research into the diagnosis, treatment and clinical outcomes of HAC. This clinical update will be the first of a two part series designed to cover the diagnosis of canine HAC and discuss current trends in the treatment of HAC.

Recently, the American College of Veterinary Internal Medicine (ACVIM) released a consensus statement that summarizes the most up-to-date information on the diagnosis of spontaneous canine HAC. The statement covers indications for screening tests and tests used to differentiate between pituitary dependent HAC (PDH) and adrenal dependent HAC (ADH).

The presentation of canine HAC can be quite varied, and dogs may display subtle clinical signs or a constellation including some or all of polyuria, polydipsia, alopecia or a pendulus abdomen. The ACVIM panel noted that the more abnormalities consistent with HAC identified on physical examination, the stronger the indication to proceed with diagnostic testing screening. Although failure to identify common clinical manifestations and laboratory abnormalities does not rule out HAC, a thorough review of the history, physical exam findings and routine laboratory tests should be performed prior to proceeding with further testing.

Tests used in the screening and diagnosis of HAC look for increased cortisol production or sensitivity of the hypothalamic-pituitary-adrenal axis to negative glucocorticoid feedback. No test for HAC has 100% diagnostic accuracy and any screening test can be negative in a patient with HAC If more then 1 screening test for HAC is negative then the potential for other diseases must be considered.

Consensus conclusions regarding screening tests are as follows:

The low dose dexamethasone suppression test (LDDST) is the screening test of choice